Why do most public toilet doors open inwards?I think you're seeing this completely the wrong way. Would you really prefer a handle on the outside part of the toilet? Some (but not all) people go into the toilet to wash their hands. They would be forced to pick up the handle with their dirty hands. The handle would get increasingly dirtier with time. After some time who would want to pick up that handle? People who go to the toilet just to urinate surely don't want to get their hands dirty before they go. The handle placed inside is definitely much cleaner than if it were placed outside.

Traffic lights: why yellow before green?Well, I'm used to the sudden green. You don't need a yellow light to prepare your car to go, you prepare it on green. What's wrong with that? I have my doubts on whether that makes so much of a difference in traffic.

Traffic lights: why yellow before green?I don't follow that. Pedestrians have flashing green lights warning that it's going to turn to red, and the red light for pedestrians shows up 3-4 seconds before the green light for cars shows. Plus, in most cases pedestrians can't see the traffic lights for cars.

Disable the save button until changes are made?@zzzzBov I don't think that's a problem with auto-save. So you want to save several versions of a document, but you don't want this version in particular? What if you don't have auto-save but hit the save button inadvertently? There should be an option to delete previous versions, but that has nothing to do with auto-save.